The present invention relates to a lubricant-feeding material for feeding a lubricant or grease to the position to be lubricated. More particularly, the present invention relates to a lubricant-feeding material which can be applied to parts subject to exposure to high temperature such as rolling bearing, linear guide apparatus and ball screw apparatus.
In general, parts requiring good lubricating properties such as bearing are filled with a lubricating composition such as lubricating oil and semisolid grease. However, these lubricating components, even if they are in the form of semisolid grease, not to mention lubricating oil, become fluidized as the temperature rises during the rotation of the bearing. In order to inhibit the scattering of these lubricating components, the filled part of the bearing must be sealed by a sealing member such as sealing plate, complicating the structure thereof. This sealing member may not be mounted on some parts such as small-sized bearing.
As a lubricating system requiring no sealing members there has been developed a solidified lubricant-feeding material composed of a mixture of a lubricating oil and a resin. This lubricant-feeding material has been put into practical use. This resin-based lubricant-feeding material allows a lubricating oil held in the resin to ooze to the surface thereof to exert a lubricating action. A polyethylene having a lubricating oil incorporated therein is disclosed in U.S. Pat. Nos. 3,729,415, 3,547,819 and 3,541,011. JP-B-63-23239 (The term xe2x80x9cJP-Bxe2x80x9d as used herein means an xe2x80x9cexamined Japanese patent publicationxe2x80x9d) discloses a lubricant-feeding composition comprising a lubricant grease held in an ultrahigh molecular polyethylene having a molecular weight of from about 1xc3x97106 to 5xc3x97106.
These lubricant-feeding compositions are worked into a material filling the bearing space formed by the inner race, outer race, rolling elements and cage of a rolling bearing as a lubricant-feeding material depending on the lubricating position.
However, the foregoing lubricant-feeding composition made of a polyethylene and a lubricating oil or grease comprises a polyethylene as a base and is thus disadvantageous in that it begins to soften at about 80xc2x0 C. and then melts completely at a temperature of from 130xc2x0 C. to 140xc2x0 C. Therefore, when the temperature is as high as not lower than 80xc2x0 C., the lubricant-feeding composition shows a drop of mechanical strength. Namely, if the lubricant-feeding composition is mounted in the bearing as a cage or fills the bearing space, there is a fear that it causes deformation or destruction while the rolling elements rotate at this high temperature.
Further, the polyethylene, which is a polyolefinic synthetic resin, has no functional groups having a high polarity, bonds (e.g., amide bond) or no aromatic rings present in its molecule and thus exhibits a poor compatibility with a lubricating oil having a high polarity such as ester oil and polyphenyl ether oil, which have excellent lubricating properties or heat resistance, or a grease comprising such a lubricating oil as a base oil. Therefore, if the polyethylene comprises such a lubricant incorporated therein singly or in combination with an oil having a low polarity being in an amount of not less than 50% by weight based on the total amount of the lubricants, it is difficult to form a lubricant-feeding material having a lubricant content of not less than 50% by weight based on the total weight of the lubricant-feeding composition. The resulting lubricant-feeding material, if successfully formed, allows the lubricant to ooze therefrom too early to maintain the desired capability of feeding a lubricant because the polyethylene exhibits an insufficient capability of holding a lubricant having a high polarity.
It is therefore an object of the present invention to provide a lubricant-feeding material which can be used at a temperature as high as from 100xc2x0 C. to 120xc2x0 C., exhibits an excellent mechanical strength and stably maintains a lubricating oil having a high polarity such as ester oil and polyphenylether oil, which have excellent lubricating properties or heat resistance, or a grease comprising such a lubricating oil as a base oil in a large amount.
The foregoing object of the present invention will become more apparent from the following detailed description and examples.
The foregoing object of the present invention is accomplished with a lubricant-feeding material comprising a polyester elastomer and at least one of a lubricating oil compatible with the polyester elastomer and a grease comprising the lubricating oil as a base oil, wherein the polyester elastomer comprises a first polyester as a hard component and a second polyester or polyether as a soft component and is solidified containing the at least one of the lubricating oil and grease and the lubricating oil oozes from the surface of the polyester elastomer.